Create Monitor

Create a monitor: subreddits to watch, or all of Reddit at once, plus an optional filter. Forward-looking only from creation (or from baseline_item_id). Every account has a free entitlement of one all-of-Reddit post watch at a 60s cadence, so no subscription is needed to create that monitor; naming a subreddit requires a paid plan and returns 402 subreddit_scope_requires_paid_plan otherwise. Requires a free monitor slot. Two separate limits apply: monitor slots, and how many DISTINCT subreddits the plan covers across all your monitors (the same subreddit named in two monitors counts once, because it is one poll stream). Returns 402 subscription_required, monitor_slots_exhausted, sitewide_slots_exhausted or distinct_subreddit_limit_reached, 501 sitewide_comment_monitoring_not_available for a sitewide comment monitor, or 400 subreddit_not_found for an unknown subreddit. Cost: Free per call.